Use the core plugin manager

I gave this a try with those other patches well not the meta but the fallback #2830031: Fix SqlBase fallback priorities and document them.

It through a lot of errors on drush ms and showed a lot of migrations that may have been from tests.

Example output:

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'cs6.node_revision' doesn't exist: SELECT COUNT(*) AS expression
FROM
(SELECT 1 AS expression
FROM
{node_revision} nr
INNER JOIN {node} n ON n.nid = nr.nid AND n.vid <> nr.vid
WHERE ((n.tnid = 0 OR n.tnid = n.nid)) AND (n.type = :db_condition_placeholder_0)) subquery; Array
(
    [:db_condition_placeholder_0] => support
)

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'cs6.node_revision' doesn't exist: SELECT COUNT(*) AS expression
FROM
(SELECT 1 AS expression
FROM
{node_revision} nr
INNER JOIN {node} n ON n.nid = nr.nid AND n.vid <> nr.vid
WHERE ((n.tnid = 0 OR n.tnid = n.nid)) AND (n.type = :db_condition_placeholder_0)) subquery; Array
(
    [:db_condition_placeholder_0] => webform
)

 Group: Default (default)                Status     Total  Imported  Unprocessed  Last imported
 d6_date_formats                         Idle       3      3         0
 d6_dblog_settings                       Idle       0      1         -1
 d6_filter_format                        Idle       5      5         0
 d6_imagecache_presets                   Idle       11     4         0
 d6_menu                                 Idle       8      8         0
 d6_path_redirect                        Importing  688    0         688
 d6_search_settings                      Idle       1      0         1
 d6_system_cron                          Idle       1      0         1
 d6_system_date                          Idle       1      0         1
 d6_system_file                          Idle       1      0         1
 d6_system_performance                   Idle       1      0         1
...

Oh but without this, I'm getting "Migration upgrade_d6_field_formatter_settings does not exist" which is weird because it's in the status list... so this seems like the right thing to do. How can I help make this work?

Still having those issues I mentioned in #5:

@mikerayn;) I'm sure it's pointing to the full database, cs6 is the database name I chose as I work for Computer Science and it's D6, I defined it in the settings.local.php. I've been using it for a while now to migrate. I built the migration using migrate-upgrade config only like this tutorial plus some custom class overrides and tweaks: https://drupalize.me/blog/201604/custom-drupal-drupal-migrations-migrate...

All the migrations are in a custom module's config/install folder. If I don't use this patch then I don't get that kind of drush ms output.

Some possible relevant config:

$databases['default']['default'] = [
  'database' => 'cs8',
  'username' => 'root',
  'password' => 'mikerayn->mikeryan',
  'prefix' => '',
  'host' => 'localhost',
  'port' => '3306',
  'namespace' => 'Drupal\\Core\\Database\\Driver\\mysql',
  'driver' => 'mysql',
];
$databases['migrate']['default'] = $databases['default']['default'];
$databases['migrate']['default']['database'] = 'cs6';

$settings['cache']['bins']['discovery_migration'] = 'cache.backend.memory';

Am I doing what you said in #14? I don't totally understand, but kinda sounds like what I'm doing...

The database connection made sense to me without documentation. Though I appreciate that I may not be doing it the way intended, it's a bit too convenient to make that mistake and likely documented like the above tutorial to do it that way.

I'm not sure what a database_state_key is, so I'll have to go read and understand what it's to do.

Ok I rebuilt the migrations as you indicated without the migrate database key and it looks better but it's still showing unexpected groups. Is it ok to be showing the 'Default' group below?

 Group: Import from Drupal 6 (migrate_drupal_6)  Status  Total  Imported  Unprocessed  Last imported
 upgrade_block_content_type                      Idle    1      0         1
 upgrade_d6_date_formats                         Idle    3      0         3
....
 upgrade_d6_term_node_revision_5                 Idle    1528   0         1528
 upgrade_d6_term_node_revision_7                 Idle    858    0         858
 upgrade_d6_upload                               Idle    217    0         217
 upgrade_d6_upload_entity_display                Idle    23     0         23
 upgrade_d6_upload_entity_form_display           Idle    23     0         23
 upgrade_d6_user_contact_settings                Idle    4863   0         4863
 Group: Default (default)                        Status  Total  Imported  Unprocessed  Last imported
 block_content_type                              Idle    1      0         1
 block_content_body_field                        Idle    1      0         1
 block_content_entity_display                    Idle    1      0         1
 block_content_entity_form_display               Idle    1      0         1
 user_picture_field                              Idle    1      0         1
 d6_upload_field                                 Idle    1      0         1

Thanks, glad to know I'm not the only one:)